For example, a power semiconductor device such as a power transistor or the like includes a semiconductor substrate having multiple semiconductor regions formed thereon and electrodes formed on both surfaces of the semiconductor substrate.
Some of power semiconductor devices are miniaturized and thinned in accordance with miniaturization of electronic equipment. The power semiconductor devices of this type generally include a relatively thin semiconductor substrate.
Conventionally, the power semiconductor device having a thin semiconductor substrate is manufactured by, for example, the following processes.
First of all, as illustrated in FIG. 4A, a semiconductor substrate 100 is prepared. In a surface region of one surface of the semiconductor substrate 100, multiple semiconductor regions are formed by impurity diffusion and the like. Multiple semiconductor devices are formed of these multiple semiconductor regions. Moreover, on the surface of the semiconductor substrate 100, electrodes such as an emitter electrode, a source electrode, etc. (not shown) are also formed.
Next, a first reinforcing member 101 is adhered to one surface of the semiconductor substrate 100 with an organic adhesive (for example, ultraviolet curable resin).
Sequentially, the other surface of the semiconductor substrate 100 is cut or etched to thin the semiconductor substrate 100 as illustrated in FIG. 4B.
When the semiconductor substrate 100 is thinned, intensity of the semiconductor substrate 100 decreases. For this reason, regarding the single use of the semiconductor substrate 100, a nick and a crack easily occur on the semiconductor substrate 100 when it is handled or transferred in the following processes. The first reinforcing member 101 prevents occurrence of the nick and the crack on the semiconductor substrate 100 and enhances the strength of the semiconductor substrate 100 in a state that it is adhered to the semiconductor substrate 100.
After that, a metallic film 102 is formed on the other surface of the semiconductor device 100 by sputtering, vacuum deposition, etc., as illustrated in FIG. 4. The metallic film 102 is patterned to form electrodes such a collector electrode, a drain electrode, and the like.
Next, a second reinforcing member 103 to which a ring-shape frame 104 is adhered to the other surface of the semiconductor substrate 100 as illustrated in FIG. 4D. The second reinforcing member 103 fixes each semiconductor device chip when, for example, the semiconductor substrate 100 is diced into the respective chips. After that, the first reinforcing member 101 is removed from the semiconductor substrate 100.
Sequentially, the semiconductor substrate 100 is divided into multiple semiconductor device chips 106 by, for example, a dicing cutter 105 as illustrated in FIG. 4E.
Then, the second reinforcing member 103 is removed from each semiconductor device chip 106. Accordingly, the semiconductor device chips 106 are individually separated and sent to a next process such as bonding and the like.
In the aforementioned conventional manufacturing process, the first reinforcing member 101 is adhered to one surface of the semiconductor substrate 100 with the organic adhesive.
However, in this method, there is a case in which components of the organic adhesive are volatilized when the metallic film 102 is being formed on the other surface of the semiconductor substrate 100, causing an adverse effect on the formation of the metallic film 102.
For example, when the semiconductor substrate 100 to which the first reinforcing member 101 is adhered is subjected to sputtering, vacuum deposition, etc., with a degree of vacuum of about 10−5 Pa and at a temperature about 100° C. to 200° C., the organic adhesive decomposes to generate gas. The gas reduces the quality of the metallic film 102.
In order to enhance the strength of the semiconductor substrate 100 and prevent the 10 reduction in the quality of the metallic film 102, it can be considered that the semiconductor substrate 100 is transferred in a state that the semiconductor substrate 100 is held by a dedicated jig. However, in the case of using the dedicated jig, the existing transferring unit, cassette, stage, etc., cannot be used, so that a unit for a manufacturing process must be changed in order to correspond to the dedicated jig.
As such, it has been difficult to prevent occurrence of the nick and the crack on the semiconductor substrate, because various problems have been found in the prevention process.
The present invention has been made in consideration of the aforementioned circumstances, and an object of the present invention is to provide a semiconductor device manufacturing method that can easily prevent occurrence of a nick and a crack on a semiconductor substrate and a ring-shaped reinforcing member used therein.
Also, an object of the present invention is to provide a semiconductor device manufacturing method that can form electrodes with high reliability and a ring-shaped reinforcing member used therein.
Furthermore, an object of the present invention is to provide a semiconductor device manufacturing method that can prevent occurrence of a nick and a crack on a semiconductor substrate without increasing manufacturing cost and a ring-shaped reinforcing member used therein.